Device for dressing crude asbestos



29, 1967 K. A. OESTERH ELD DEVICE FOR DRESSING CRUDE ASBESTOS 2 Sheets-Sheet 1 Filed March 5, 1964 mum/rap KARL A. 055 TEE/#20 ATTY g- 1967 K. A. OESTERHELD DEVICE FOR DRESSING CRUDE ASBESTOS 2 Sheets-Sheet 2 Filed March 5, 1964 QSEQEQEQQ ARL 0557573 1 0 ATTYS,

United States Patent Ofilice 3,337,922 Patented Aug. 29, 1967 8 Claims. (01. 19-66) This invention relates to a device for dressing the bunch-like adhered asbestos natural state fibres separated from the source rock, in which the fibre bunches suspended in a liquid are passed between friction surfaces under high, controllable hydraulic pressure so that the fibres are bent to and fro in constantly varying directions and thereby the fibre bunches are opened up. For carrying out this method a device has become known in which a narrow passage gap is defined between a rigid shaft rotatably mounted in a cylindrical housing provided with an elastic lining, and the housing surrounding the shaft, which gap is of equal width all through or in which narrow and wide passage gap sections alternate with each other. Further it has been suggested to mount a conical drum on the shaft and to devise at least the outer cone shell thereof so as to be resilient or to provide the inner surface of the tapered housing with a resilient lining so that between the conical drum and the inner wall of the housing there is available a narrow passage gap of equal width all through, which lies on the conical surface of a frustum.

Bending the fibres to and fro in constantly varying direction represents a fulling action which has proved very advantageous for completely dressing the bunch-like adhered asbestos natural state fibres at the same time avoiding injury to the fibres.

It is the object of the present invention to produce a dressing'device of the specified type which has an improved fulling capacity and thus an increased fibre dressing capacity.

The invention provides a device for dressing adhered asbestos natural state fibres separated from the source rock and suspended, in a liquid, of the type including a housing closed at least at one end by a cover, and a drum rotatably mounted within said housing by means of a drum shaft so as to define an annular passage between said drum and said housing surrounding said drum, said passage being adapted to receive said fibres suspended in the liquid to form a fibre-liquid mixture forced through said passage under controllable hydraulic pressure and repeated bending of said fibres to and fro in constantly varying directions, characterized in that said housing and said drum are of cylindrical shape, said cylindrical drum has two circular end walls, an eccentric bore is provided in either of said circular end walls of said cylindrical drum, a hub is seated in either of said eccentric bores and on said drum shaft so that said cylindrical drum extends within said cylindrical housing in eccentric relationship to said cylindrical housing, at least one end of said cylindrical drum is adapted to define a discharge end for treated fibre-liquid mixture, a baffle plate is associated with said discharge end and mounted on the respective hub so as to be concentric with said cylindrical housing and to define together with said cylindrical housing a circular ring gap narrowed in relation to said annular passage.

Conveniently, a mechanism may be provided and connected With the drum shaft for reciprocating the drum shaft by relatively short strokes in the axial direction and during rotation thereof.

By a dressing device designed in this manner, the fibres will be repeatedly subjected to momentary increased pressure and thus still more intensively fulled.

With certain kinds of asbestos, e.g. South African blue asbestos, the complete dressing of which is very difficult owing to their particular fibre structure, faster disentangling of the fibre bunches and a better degree of dressing will be attained by the increased fulling. Damage to the fibres owing to the action of mechanically applied pressure brought about by the eccentric rotation of the drum in the housing or by the axially reciprocating motion of the drum is avoided because the fibres are acted upon by the pressure substantially transversely of the longitudinal direction of the fibres so that the fibres, consequently, are not subjected to tension which might rupture the fibres.

The eccentric rotation and the oscillating motion of the drum result in the best falling effect possible when both measures are applied in combination. In some cases, however, where it is the question of dressing soft fibres, the application of eccentric rotation will generally be sufficient.

To permit regulation of the transit time of the fibreliquid mixture in the dressing device in accordance with the kind and quality of the asbestos material to be dressed, it is provided by a further development of the invention that an adjustable and lockable hinged trap may be incorporated in a recess in the bottom of the cylindrical housing in the region of the discharge end portion of the horizontally arranged drum and serve as a regulating trap for draining off the treated fibre-liquid mixture or any desired portion thereof before this passes through the narrowed circular ring gap. Conveniently, a discharge funnel may be connected to the bottom of the housing to receive the quantities of the fibre-liquid mixture issuing through the open hinged trap as well as through the narrowed circular ring gap. Whereas with completely closed regulating trap the fibre-liquid mixture fed under high hydraulic pressure will issue through the narrowed annular gap defined by the bafiie plate, after having rotated several times together with the rotating drum, the number of rotations of the fibre-liquid mixture within the housing can be reduced as desired by opening the hinged trap more or less, thereby to adapt the duration of the fulling treatment in a simple manner to actual requirements so that the best degree possible of opening the asbestos material is attainable at any time.

According to a preferred embodiment of the invention, the cylindrical drum extends in a horizontal position within the cylindrical housing, a bottom aperture is provided between the baffle plate and the cover of the housing, an opening is defined in the bottom of said housing in the region covered by the discharge end of the drum, a hinged trap is incorporated in the opening so as to be adjustable and lockable, the hinged trap serving as a regulating trap for discharging a controllable quantity of the treated fibre-liquid mixture from the housing before said quantity of treated fibre-liquid mixture passes through the circular ring gap, and a discharge funnel is connected to the bottom of the housing at said discharge end of the drum and extends across the bottom aperture and the opening including the regulating trap.

For producing the reciprocating motion of the drum shaft, a suitable gearing may be incorporated and -connected in series with the motor driving the shaft. However,

since the drum shaft is not intended to effect such reciprocating motion upon each rotation thereof, the mechanism for reciprocating the drum shaft may include a flange seated on the drum shaft outside the cylindrical housing, an auxiliary shaft, two cam plates mounted on the auxiliary shaft in axially spaced relationship to each other, a double-armed lever, a sliding member secured to one lever arm of the double-armed lever and guided between the cam plates; and a pair of rollers provided on the outer lever arm of the double-armed lever and contacting opposite end faces of the flange.

Since the crude asbestos material is to be dressed in a manner taking care of the fibres in the best way possible,

it is advisable to provide either the cylindrical inner wall of the housing or the cylindrically curved outer surface of the drum, which constitute cooperating friction surfaces, with a resilient coating of rubber or rubber-like plastic. In order to produce in this case an intense friction in addition to the fulling effect, small circumferential grooves may be provided in the cooperating friction surfaces, for example in the cylindrical inner wall of the housing and in the rubber or plastic coating of the drum.

Two preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a vertical longitudinal central section through a schematically drawn device according to the invention;

FIG. 2 is a cross section taken on the line IIII of FIG. 1;

FIG. 3 is a partial longitudinal section, as in FIG. 1, through a similar device having cooperating friction surfaces of a diiferent design;

FIG. 3a shows a detail of FIG. 3 on an enlarged scale; and

FIG. 3a is an enlarged sectional view taken generally along line IIIa of FIG. 3, and more clearly illustrates the configuration of the rubber coating carried by the drum and the generally complementary configuration of the cylindrical housing.

FIG. 1 shows a dressing device according to the present invention, having a cylindrical housing 1, which is stationarily arranged on supporting legs 28 on a horizontal position and closed at both ends by covers 3 bolted thereto. A shaft 5, which is rotatably and axially displaceably supported in two bearings 29 disposed at either end of the housing 1, extends through central bores in the two covers 3. The shaft carries a drum consisting of a cylindrical rigid drum shell 30 and of two circular end walls 32 provided with eccentric bores.

Hubs 31 are fitted in the eccentric bores in the end walls 32 of the drum and fixed on the shaft 5 so that the drum occupies an eccentric position in the housing 1 and a resilient coating 33 of rubber or plastic, which is applied to the curved outer surface of the drum shell 30, is spaced along a certain apex line thereof, from the cylindrical inner wall of the housing 1 by the smallest distance of, for example, 0.5 mm. and along the diametrically opposite apex line by the largest distance of, for example, 5 mm., leaving between the drum shell 30 or its coating 33 and the inner cylindrical surface of the housing an annular passage of varying clearance for a fibre-liquid mixture to be forced therethrough during the dressing operation. Either end of the drum is associated with a baffie plate 34 seated with a central middle bore on the respective hub 31. The baffie plates 34 are so dimensioned with regard to their outer diameter that their rim edges terminate at a small distance, for example, of 0.5 mm., from the cylindrical inner wall of the housing 1 and in conjunction with the inner wall of the housing define circular ring gaps 35 narrowed in relation to the annular passage. When the drum shaft 5 is rotated by a variable speed electric motor, not shown, or another suitable driving motor, the cylindrical drum shaft 30 will eccentrically rotate within the housing 1 so that the largest clearance of the annular passage between the drum shell coating 33 and the inner wall of the housing, which largest clearance in the position of rotation of the drum plotted in FIGS. 1 and 2 is situated at the upper apex line of the drum shell 30, and consequently also the smallest clearance of the annular passage will continuously change their position during rotation of the drum.

The fibre-liquid mixture with the bunch-like adhered asbestos fibres to be dressed will be forced under high hydraulic pressure by means of a feed pump, not shown, through a short feed pipe 36, which is arranged in the central region of the housing 1 on an upwards facing portion of the wall of the housing, into the eccentric annular passage between the resilient drum coating 33 and the inner wall of the housing 1. The fibre-liquid mixture will be forced in opposite directions through the annular passage and dragged along by the rotating drum in the circumferential direction thereof. During rotation, the bunches of fibres repeatedly reach the smallest passage clearance and are vigorously fulled between the resilient drum coating 33 and the rigid inner wall of the housing 1, with the result that the individual fibres are separated from the bunches of fibres and dressed without being damaged or ruptured.

Finally, the fibre-liquid mixture will pass together with the fibres separated from the bunches through the narrow circular ring gaps 35 into chambers 37 defined between the baffie plates 34 and the covers 3 of the housing 1, fro-m which chambers 37 it is guided through funnels 39 arranged under bottom apertures 38 of the housing 1 and through a conduit, not shown, to a further processing station or back into the dressing device for repeated treatment when, in the case of asbestos material particularly hard to dress, during the first transit through the dressing device the desired degree of dressing of the fibrous material has not yet been attained. Stirring paddles 40 secured to the drum shaft 5 within the chambers 37 take care that the fibre-liquid mixture is continuously discharged from the chambers 37.

When dressing asbestos material in which the individual fibres are not tightly adhered, it is possible to shorten the duration of treatment to a period of time sufiicient for this material, in that the discharge throttling brought about by the baffle plates 34 is partly or even completely eliminated. For this purpose, openings 41 are defined in the bottom portion of the housing 1 in the regions covered by the discharge ends of the drum and regulating traps 43 are hinged on axles 42 (FIG. 2) on the rear transverse edges, with respect to the direction of rotation of the drum, of the openings 41, and cover the openings 41 when being in their closed positions. Either of the two traps 43 can be swung away from the Wall of the housing to the extent desired by operating an adjusting spindle 44, so that it clears with its side opposite the hinge axle 42 .a more or less large discharge gap in the wall of the housing 1, through which a controllable portion of the fibre-liquid mixture or, in the case of completely opened traps 43 all of the supplied fibre-liquid mixture can bypass the narrow circular ring gap 35 and issue from the housing 1 without having to pass through the circular ring gap 35. By appropriately adjusting the regulating traps 43 it is possible to reduce the number of rotations, which the fibre-liquid mixture carries out together with the drum in the housing 1, and thus to accurately adjust in each case the transit time for the kind of asbestos material to be dressed.

As shown particularly in FIG. 2, each adjusting spindle 44 consists of a threaded rod 44a, which is rotatably but axially immovably mounted on a rotatable sleeve 45 of a bracket 46 arranged outside the discharge funnel 39, and of a threaded tube 441), screwed on the threaded rod 44a, which tube 441; is led by means of rubber bellows in a liquid-tight manner through an opening in one of the walls of the funnel 39, and pivoted to an eye 47 on the hinged trap 43. By turning the threaded rod 44a fitted with a hand wheel so that the threaded tube 441) is screwed further on to the threaded rod 44a, the hinged trap 43 is moved away from the Wall of the housing 1, whereas by turning the threaded rod 44a in the opposite direction of rotation, the hinged trap 43 will be swung towards the wall of the housing 1 and close the opening 41.

The discharge funnels 39 are so designed that they extend across the permanently open bottom aperture 38 situated under the chamber 37 in the housing 1 and across the adjacent opening 41 with its regulating trap 43, to receive the quantities of the fibre-liquid mixture which issue through the latter as well as, if desired, through the bottom aperture 38 via the baffle bers 37.

During its rotatory movement, the drum shaft is adapted to perform together with the drum mounted thereon an axially reciprocating short-stroke motion Within the housing 1, which motion is so harmonized with the number of revolutions of the drum that the drum is pushed to and fro once upon a determined number of revolutions. The axially reciprocating motion of the drum shaft 5 is derived, as can be seen from FIG. 1, from an auxiliary shaft 48 rotated by the motor driving the drum shaft 5, through the intermediary of a reduction gear, both not shown. Between two cam plates 49 fixed on the auxiliary shaft 48 there is guided a sliding member 50. The sliding member 50 is seated at the end of an arm of a double-arm lever 51 which is pivoted about a hinge bolt 53 on a stationary bracket 52. On the two legs of a fork 54, which is disposed on the other arm of the doublearmed lever 51, two convexly turned rollers 55 are rotatably mounted to contact the two opposite end faces of a flange 56 fixed on the drum shaft 5 for transmitting the rocking movement of the double-armed lever 51, which is caused by the cam plates 49, to the drum shaft 5. The short-stroke reciprocation of the rotating drum shaft 5 assists the fulling of the fibre bunches to be dressed and, together with the eccentric rotation of the drum in the housing 1, results in extraordinarily intensive fulling of the fibres. In this manner it is achieved to completely dress even such asbestos material as has been hitherto particularly hard to dress. At the same time, the resilient coating 33 of the rigid drum shell 30 ensures careful treatment of the delicate fibres.

In the dressing device shown in FIG. 3, small circumferential grooves 57 and 58 are defined in the inner wall of the housing 1 and in the outer surface of the resilient rubber or plastic coating 33 of the drum, i.e., in the cooperating friction surfaces. For the sake of clearness, the grooves 57 and 58 are represented excessively large in FIG. '3; in reality they have but a depth of about 3.0 mm. and a width of about 15.0 mm. The grooves 57 and 58 cause an increased friction of the material to be treated between the cooperating friction surfaces constituted -by the resilient coating 33 of the drum shell 30 and the inner wall of the housing 1, which again has a favourable effect on the fulling of the fibers.

I claim:

1. A device for dressing adhered asbestos natural state fibers separated from the source rock and suspended in a liquid comprising a cylindrical housing, a cover for each end of the housing having aligned drum shaft openings therein, a drum shaft extending through said cover openings, a cylindrical drum rotatably mounted on said drum shaft and rotatable within sa-id housing and defining an annular passage between said drum and said housing, said passage being adapted to receive asbestos fibers suspended in a liquid that is forced through said passage under controllable hydraulic pressure, the opposed faces of the housing and drum being grooved, means for reciprocating the drum longitudinally of the housing for repeated bending of said fibers in constantly varying directions, a cylindrical end wall for each end of said cylindrical drum with a bore therein, a hub in each bore through which the drum extends, each end of said cylindrical housing having a discharge aperture for the treated fiber liquid mixture, a baflie plate in each end of the housing outwardly of the end walls of the drum and mounted on plate 34 and the chamsaid drum shaft inwardly of said discharge apertures for cooperation with said cylindrical housing to form a circu-lar ring gap narrowed in relation to said annular passage.

2. A device as set forth in claim 1, wherein the means for reciprocating the drum shaft includes mechanism connected with said drum shaft for reciprocating said drum shaft by relatively short strokes in the axial direction and during rotation thereof.

3. A device as set forth in claim 1 wherein said cylindrical drum extends in a horizontal position within said cylindrical housing, there being an opening in the bottom of said housing adjacent each end thereof inwardly of the baffle plates in the region covered by each end of said drum, a hinge-d trap incorporated in said opening so as to be adjustable and lockable, said hinged trap serving as a regulating trap for discharging a controllable quantity of said treated fiber liquid mixture from said housing before said quanti-ty of treated fiber liquid mixture passes through said circular ring gap and a discharge funnel connected to the bottom of said housing at each end of said drum and extending across said discharge aperture and said opening including said regulating trap.

4. A device as set forth in claim 1 wherein the mechanism for reciprocating said drum shaft includes a flange on said drum shaft exteriorly of one end of said cylindrical housing, an axiliary shaft, two cam plates mounted on said auxiliary shaft in axially spaced relationship to each other, a double-armed lever, a sliding member secure-d to one lever arm of said double-armed lever and guided between said cam plates, and a pair of rollers provided on the, other lever arm of said double-armed lever and contacting opposite end faces of said flange.

5. A device as set forth in claim 1 wherein the inner cylindrical surface of said housing and the outer cylindrical surface of said drum have cooperating friction sur faces.

6. A device as set forth in claim 5 wherein one of said cooperating friction surfaces is provided with a coating of resilient material.

7. A device as set forth in claim 6 wherein said resilient material is rubber.

8. A device as set forth in claim 6 wherein said resilient material is plastic.

References Cited UNITED STATES PATENTS 7,072 2/1850 Jackson et val. 19-100 773,479 10/ 1904 Cornell 241-205 X 838,370 11/1906 Belt et al. 241-221 X 1,799,685 4/ 1931 Gminder. 1,971,335 8/1934 Benner et al. 241-205 1,980,589 11/1934 Acree 241-221 X 2,173,975 9/1939 Lyons 241-21 X 2,309,376 1/1943 Avery 241-254 3,221,999 12/1965 Cumpston 241-255 X 3,228,067 1/1966 Strang et al. 19-66 FOREIGN PATENTS 183,631 10/ 1955 Austria. 1,083,767 6/ 1954 France.

317,981 8/ 1929' Great Britain.

680,576 10/ 1952 Great Britain.

MERVIN STEIN, Primary Examiner. I). NEWTON, Assistant Examiner, 

1. A DEVICE FOR DRESSING ADHERED ASBESTOS NATURAL STATE FIBERS SEPARATED FROM THE SOURCE ROCK AND SUSPENDED IN A LIQUID COMPRISING A CYLINDRICAL HOUSING, A COVER FOR EACH END OF THE HOUSING HAVING ALIGNED DRUM SHAFT OPENINGS THEREIN, A DRUM SHAFT EXTENDING THROUGH SAID COVER OPENINGS, A CYLINDRICAL DRUM ROTATABLE MOUNTED ON SAID DRUM SHAFT AND ROTATABLE WITHIN SAID HOUSING AND DEFINING AN ANNULAR PASSAGE BETWEEN SAID DRUM AND SAID HOUSING, SAID PASSAGE BEING ADAPTED TO RECEIVE ASBESTOS FIBERS SUSPENDED IN A LIQUID THT IS FORCES THROUGH SAID PASSAGE UNDER CONTROLLABLE HYDRAULIC PRESSURE, THE OPPOSED FACES OF THE HOUSING AND DRUM BEING GROOVED, MEANS FOR RECIPROCATING THE DRUM LONGITUDINALLY OF THE HOUSING FOR REPEATED BENDING OF SAID FIBERS IN CONSTANTLY VARYING DIRECTIONS, A CYLINDRICAL END WALL FOR EACH END OF SAID CYLINDRICAL DRUM WITH A BORE THEREIN, A HUB IN EACH BORE THROUGH WHICH THE DRUM EXTENDS, EACH END OF SAID CYLINDRICAL HOUSING HAVING DISCHARGE APERTURE FOR THE TREATED FIBER LIQUID MIXTURE, A BAFFLE PLATE IN EACH END OF THE HOUSING OUTWARDLY OF THE END WALLS OF THE DRUM AND MOUNTED ON SAID DRUM SHAFT INWARDLY OF SAID DISCHARGE APERTURES FOR COOPERATION WITH SAID CYLINDRICAL HOUSING TO FORM A CIRCULAR RING GAP NARROWED IN RELATION TO SAID ANNULAR PASSAGE. 